THERMAL PERFORMANCE OF GRANULAR PCM AND DEVELOPMENT OF SALT HYDRATE EUTECTICS FOR AIR CONDITIONING

摘要

The granular phase change material (PCM) Rubitherm PK 6 has been investigated for the application of cold water supply in air conditioning systems. It is a compound of paraffin and a plastic matrix with granule sizes of about 5 mm. The PCM is used as a packed bed with water as heat transfer fluid. Experimental results show high performances compared to previous measurements with other macro scale encapsulations like spheres and plastic pouches. In addition a systematic search for binary and ternary eutectics of inorganic salts and salt hydrates with melting temperatures between 4 and 25°C has been performed by means of differential scanning calorimetry (DSC). Here, the ternary system of Zn(NO_3)_2 · 6 H_2O, Mn(NO_3)_2 · 4 H_2O and KNO_3 with an melting temperature range 18 - 21°C is presented. Suitable nucleating and thickening agents have been found and tested to prevent the mixture from subcooling and phase separation.